U.S. patent number 6,137,262 [Application Number 09/246,516] was granted by the patent office on 2000-10-24 for process and arrangement for monitoring and/or controlling charging of a modular battery, particularly in a battery powered vehicle.
This patent grant is currently assigned to Volkswagen AG. Invention is credited to Karl-Heinz Hauer.
United States Patent |
6,137,262 |
Hauer |
October 24, 2000 |
Process and arrangement for monitoring and/or controlling charging
of a modular battery, particularly in a battery powered vehicle
Abstract
In a process and arrangement for monitoring and/or controlling
charging of a battery, particularly in a battery-powered vehicle,
test data relevant to the monitoring are detected at the battery
and sent to an evaluation unit through a power cable connecting the
battery to at least one power consuming component. The evaluation
unit is connected to the power cable and the test data are
transmitted to the evaluation unit through the power cable using a
coded alternating voltage. This eliminates the need for additional
insulated signaling lines connecting the battery sensors to the
evaluation unit and reduces the need for complicated wiring,
particularly in batteries with modular construction as used in
battery driven automobiles.
Inventors: |
Hauer; Karl-Heinz
(Braunschweig, DE) |
Assignee: |
Volkswagen AG (Wolfsburg,
DE)
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Family
ID: |
7802283 |
Appl.
No.: |
09/246,516 |
Filed: |
February 9, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCTEP9703345 |
Jun 26, 1997 |
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Foreign Application Priority Data
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Aug 9, 1996 [DE] |
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196 32 253 |
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Current U.S.
Class: |
320/132;
320/130 |
Current CPC
Class: |
H02J
7/0021 (20130101); H02J 7/00047 (20200101); H02J
7/00036 (20200101); Y02T 10/70 (20130101) |
Current International
Class: |
H02J
7/00 (20060101); H02J 007/00 () |
Field of
Search: |
;320/132,130,103,106,107 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0470065 |
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Jul 1991 |
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EP |
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0693814 |
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Jul 1995 |
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EP |
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2399150 |
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Feb 1979 |
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FR |
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2589008 |
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Apr 1987 |
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FR |
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3706076 |
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Sep 1988 |
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DE |
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4105369 |
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Feb 1992 |
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DE |
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4422005 |
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Dec 1995 |
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DE |
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Primary Examiner: Riley; Shawn
Assistant Examiner: Luk; Lawrence
Attorney, Agent or Firm: Baker Botts L.L.P.
Parent Case Text
REFERENCE TO RELATED APPLICATION
This application is a continuation of International Application
Ser. No. PCT/EP97/03345, filed Jun. 26, 1997.
Claims
I claim:
1. A process for monitoring and/or controlling charging of a
battery having power cables for supplying electric power to at
least one power consuming component comprising:
detecting at the battery measurement data relating to the condition
of the battery; and
transmitting measurement data from the battery to an evaluation
unit by applying coded alternating voltage signals representing
measurement data to a battery power cable.
2. A process in accordance with claim 1 wherein the measurement
data are transmitted by frequency modulated alternating voltage
signals.
3. A process in accordance with claim 1 wherein the measurement
data include temperature data and voltage data.
4. A process in accordance with claim 1 wherein the battery
comprises a plurality of individual modules and the measurement
data are detected at the individual modules and are transmitted
over a power cable directly to the evaluation unit.
5. A process in accordance with claim 1 wherein the battery
comprises a plurality of individual modules and the measurement
data are detected at individual modules and are transmitted through
other modules to the evaluation unit.
6. A process in accordance with claim 1 wherein the battery
comprises a plurality of individual modules and, for simultaneous
acquisition of measurement data at the individual modules, the
measurement is initiated by the evaluation unit and the measurement
data are buffered in each module, and wherein each module has a
module address by which the buffered measurement data are polled
and evaluated by the evaluation unit.
7. A process in accordance with claim 6 wherein a circuit employed
for triggering the measurements and for transmitting the
measurement data switches itself to a state of readiness as a
so-called "sleep mode" with low energy consumption when the circuit
is not triggered for detection of measurement data and no
measurement data are being transmitted.
8. An arrangement for monitoring and/or controlling charging of a
modular battery comprising a plurality of measurement transducers
each associated with a corresponding one of a plurality of modules
of a modular battery; a central evaluation unit; a power cable
connecting the battery to a power consuming component; and an
output from each measurement transducer for applying measurement
signals from the transducers through the battery cable to the
central evaluation unit.
9. An arrangement in accordance with claim 8 wherein each module to
be monitored has a module controller which is connected to a
central evaluation unit through the power cable.
10. An arrangement in accordance with claim 9 including an
oscillator circuit in each module for generating an alternating
voltage which is applied to the power cable utilizing an internal
impedance of each individual module and a capacitor of the
corresponding module controller, which alternating voltage can be
evaluated by the central evaluation unit.
11. An arrangement in accordance with claim 8 including an
oscillator circuit for generating an alternating voltage which can
be activated by the central evaluation unit, utilizing an internal
resistance of a battery module and a capacitor in the evaluation
unit, which alternating voltage can be evaluated by each of the
individual module controllers.
12. An arrangement in accordance with claim 8 including a storage
circuit associated with each module for buffering of digitized
measurement data from the corresponding module detected after a
triggering by the central evaluation unit, and wherein the central
evaluation unit contains control means for serial polling of the
buffered measurement data in the storage circuits of the
modules.
13. An arrangement in accordance with claim 12 wherein each storage
circuit is integrated in the corresponding module controller.
14. An arrangement in accordance with claim 9 wherein the module
controllers are supplied with voltage directly from the
modules.
15. An arrangement in accordance with claim 9 wherein each of the
module controllers is integrated in the corresponding module.
Description
BACKGROUND OF INVENTION
This invention relates to processes and arrangements for monitoring
and/or controlling charging of a modular battery, particularly in
battery powered vehicles.
Electric vehicles which derive their power from rechargeable
batteries, particularly from lead storage batteries connected in
series, are already used for a variety of purposes. Such
environmentally friendly electric power systems are beginning to
gain increasing acceptance in road vehicles.
A significant problem encountered in such applications is
monitoring the operational readiness of the battery modules and
displaying indications of their state of readiness.
Even in other applications of batteries, for instance starter
batteries for vehicles, the condition of the battery charge and an
appropriate indication of that condition is important to a user. A
large number of different processes for determining the operational
condition of a battery are known.
For example, German Offenlegungsschrift No. 37 06 076 discloses the
determination of the density of the battery acid for ascertaining
the charge condition of the battery. This process is relatively
costly for continuous detection and indication by a remote
indicator.
In addition, U.S. Pat. No. 5,598,088 discloses a process for
determining the charge condition of a battery from a charge balance
by evaluating the charging current and the discharge current. In
order to obtain as precise an indication of the battery charge
condition as possible, additional corrections are applied which
take into account the magnitude of the current, the temperature,
and the age of the battery. In a similar process disclosed in U.S.
Pat. No. 4,888,716, in which the service life of a motor vehicle
battery is also determined and indicated, the terminal voltage, the
charging and discharge current, and the temperature of a battery
are detected and processed in an evaluation circuit and the result
is displayed in an indicator unit.
German Offenlegingsschrift No. 37 06 076 also discloses a process
in which the terminal voltage of a battery is sampled at discrete
time intervals and the result is compared with values of a
characteristic curve to determine the charge condition of the
battery.
U.S. Pat. No. 5,635,820 describes a process for controlling the
charging of a battery for an electric vehicle in which the battery
temperature, the battery voltage and the charging current are
detected and evaluated in a charge control device.
In the prior art battery monitoring and charge control systems
mentioned above, measurement transducers are required on the
battery or the battery modules and cells for detecting the
necessary measurement data and, in addition to the power cables for
the battery, signal lines which are electrically isolated from the
power cables of the battery extend from the measurement transducers
to the control and evaluation circuits. Consequently, a high
expenditure is required for signal lines, especially for modular
batteries such as those used in electric vehicles.
German Patent No. 41 05 369 discloses a charge condition
indicator
arrangement for a battery in a remote control transmitter for
information processing devices, particularly for consumer
electronics devices such as radio or television units or video
recorders. In this arrangement, measurement data for determining
the charge condition of the battery are detected in the remote
control transmitter and transmitted without wires via a
transmission medium such as infrared light, ultrasound or
electromagnetic waves to the device to be controlled. The device to
be controlled contains an evaluation circuit and a display element
to indicate the battery charge condition. Such wireless
transmission of measurement data detected at the battery to an
evaluation unit is only possible under favorable conditions, and in
particular is not suitable for a motor vehicle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a process
and arrangement for monitoring and/or controlling the charging of a
battery which overcomes disadvantages of the prior art.
Another object of the invention is to provide a battery monitoring
process and arrangement in which the operating condition of a
battery can be monitored effectively at low cost.
These and other objects of the invention are attained by providing
a process and arrangement for monitoring and/or controlling the
charge condition of a battery in which charge condition data are
transmitted by coded alternating current signals from the battery
to an evaluation unit through power cables connected to the
battery.
Thus, in accordance with the invention, measurement data detected
directly at the battery, in particular the battery terminal voltage
and the temperature, are transmitted over the power cables to the
evaluation unit by coded alternating voltage signals.
As a result, the signal lines required in the prior art
arrangements can be omitted entirely and electrical isolation is no
longer necessary. In comparison with the cost of the additional
signal lines required by the prior art, the circuit expenditure
required for coded transmission of the measurement data to provide
an indication of the operational condition of the overall
arrangement is far lower, particularly when batteries are used that
contain a large number of modules and/or cells each of which is
separately monitored.
The measured values for each cell or module can be transmitted in
coded form directly to the evaluation unit or they can be forwarded
to other modules and/or cells and then retransmitted from there to
the evaluation unit.
In this context, the data transmission is advantageously serial and
frequency modulated. Simultaneous detection of measurement data
from the individual modules is important for the evaluation of the
operational condition of a battery consisting of individual modules
in an overall battery arrangement. To this end, the detection of
measurement data is advantageously triggered by the central
evaluation unit so that the measurement are simultaneously made at
all of the modules. The resulting measurement data are digitized
and then buffered in storage circuits in the modules and from there
are serially polled and evaluated by the evaluation unit in which
each module is assigned an addressable module address.
To reduce energy consumption, measurement and data storage and
transmission circuits are maintained in a state of readiness as a
so-called "sleep mode" when the circuits are not triggered for
simultaneous detection of measurement data and no measurement data
are being transmitted to the evaluation unit.
In an arrangement for carrying out the process of data transmission
on battery power cables in accordance with the invention, a
conventional oscillating circuit is used to generate an alternating
voltage in which a modulation voltage falls as a result of the
excitation of the oscillating circuit at the battery and/or the
modules and/or the cells. A microcomputer is used to evaluate the
measurement data. In this arrangement the evaluation circuit can be
integrated into a microcomputer that is also used for other
functions.
Advantageously, storage circuits for buffering of measurement data
are integrated into every module so that no expensive cabling is
required between the measurement transducers and the buffers.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the invention will be apparent
from a reading of the following description in conjunction with the
accompanying drawings, in which:
FIG. 1 is a schematic block diagram showing a representative
embodiment of an arrangement for monitoring the charge condition of
a battery in accordance with the invention; and
FIG. 2 is a schematic circuit diagram showing a representative
series-resonant circuit for the transmission of measurement data
with a coded alternating voltage for use in the invention.
DESCRIPTION OF PREFERRED EMBODIMENT
In the typical embodiment of the invention schematically
illustrated in FIG. 1, a battery 1 supplies electrical power
through two power cables 2 and 3 to power consuming components that
are shown schematically as a load resistance 4. Contained in power
cable 2 are a measuring shunt 5 and a master switch 6. The
measuring shunt 5 is connected through two measurement lines 7 and
8 to a central evaluation unit 9 which is also connected to the
power cables 2 and 3 by two signal lines 10 and 11.
In the illustrated arrangement, the battery 1 constitutes the
energy source for a battery powered vehicle and the load resistance
4 essentially represents an electric drive motor for the vehicle.
Where ordinary lead storage batteries are used, the battery 1 is
modular, consisting of a series of connected cells or modules
12-17. Integrated in the modules 12-17 are corresponding module
circuits constituting module controllers 19-24.
Each of the module controllers 19-24 has two terminals 25 and 26
which are connected as shown in FIG. 1to corresponding terminals 25
and 26 of each of the other modules 12-17 for detecting the
terminal voltage. In addition, each of the module controllers 19-24
is connected to one or more additional measurement transducers (not
shown) associated with each module, for example temperature
transducers.
The central evaluation unit 9 contains, in particular, high-voltage
filters, rectifiers, amplifiers and a microcomputer.
The module controllers 19-24 also include digitizing and buffering
devices that work together with the central evaluation unit 9, as
well as a connection to a seriesresonant circuit by which an
alternating voltage containing the buffered measurement data can be
transmitted.
The region 27 surrounded by a dashed line on the battery side in
the schematic circuit diagram shown in FIG. 2, includes a module 28
of the battery, an ohmic resistance R1 and an inductance L2
representing the complex internal impedance of the battery. The
inductances L2 and L3 represent the line inductances of the
leads.
The remaining portion of the circuit is associated with the module
controller. The leads with the inductances L2 and L3 are connected
to a transistor Q2 that, in conjunction with four resistors R2, R3,
R4, R5 and a capacitor C1, forms a series-resonant circuit that is
driven at a frequency close to its resonant frequency.
An alternating voltage that is generated by an oscillator 31 is
applied through an additional capacitor C2 to the junction of the
resistors R3, R4 and R5. In addition, the positive pole 29 in the
circuit section containing the battery is connected through an
inductance L4 to the resistor R4 and also to ground 30 through a
smoothing capacitor C3.
The circuit section of the central evaluation unit 9 for the
transmission of coded information has a similar arrangement but
differs in the tuning of the oscillating circuit L1, R1, L2, L3,
and C1, since the entire battery 1 provides the voltage source
28.
The arrangement shown in FIGS. 1 and 2 operates in the following
manner:
The module voltage and the module temperature are detected at each
of the individual modules 12-17. If a module consists of several
cells, each of the cells are likewise monitored with respect to its
voltage condition.
The detecting circuits are activated by the central evaluation unit
9 for simultaneous measurement at all modules. The communication
between the central evaluation unit 9 acting as a master and the
module controllers 19 through 24 acting as slaves is always
initialized from the master. The command "start measurement" thus
applies for all module controllers. It initializes a voltage
measurement and/or temperature measurement and the measurement data
are digitized and buffered in a storage unit of the module
controller.
Subsequently, the buffered measurement data are polled sequentially
by the central evaluation unit 9. To this end, an address code is
transmitted to each of the modules over the power cables. The
addressed module controllers answer in the echo process, in which
each buffered voltage value and temperature value is transmitted
one at a time from a module controller to the central evaluation
unit with the aid of one start bit (low potential), 8 data bits and
one stop bit (high potential). Thereafter, the next module
controller is polled. After all measured values have been received
by the central evaluation unit, the evaluation is undertaken using
conventional criteria, and the charge condition of the battery is
indicated.
Although the invention has been described herein with reference to
specific embodiments, many modifications and variations therein
will readily occur to those skilled in the art. Accordingly, all
such variations and modifications are included within the intended
scope of the invention.
* * * * *